An early antecedent to mathcore was practiced by Black Flag, in 1984, with the album My War: "Its seven-minute metal dirges and fusion-style time signatures proved too much for many fans".[10] Many groups from the mathcore scene paid tribute to Black Flag for the album Black on Black.[11]

The portmanteau term "mathcore" emphasizes the influence taken from math rock: math rock with hardcore. The earliest known bands to record this hybrid include Rorschach, Starkweather, Botch, and Converge. Throughout the 1990s, several other groups started to emerge: Cave In from Massachusetts, Cable from Connecticut, Coalesce from Kansas City, and Knut from Switzerland. The term mathcore was coined at the release of The Dillinger Escape Plan's 1999 debut album Calculating Infinity. The Dillinger Escape Plan is often considered the "pioneer" of mathcore.[13] Before the term "mathcore", the style had only been referred to as "noisecore",[8][14] though the genre's existence before this time is generally recognized.

The term is generally applied by journalists, rather than by musicians themselves. Jacob Bannon of Converge stated

“

I really don't know what mathcore is. Converge is an aggressive band. We have elements of hardcore, punk, and metal for sure. But I think trying to define our efforts and other bands with a generic sub-genre [sic] name is counter productive. We all have something unique to offer and should be celebrated for those qualities rather than having them generalized for easy consumption.[24]